I thought I should just point out being someone who is properly looking into game development myself now, if you do make a
competitive game where you can win Bitcoin, it absolutely fucking has to be perfectly balanced in terms of statistics, that means no silly powerups, no RPG levelling, all the stats have to be completely equal. I say this because while it would be a fun thing to do I see so many of these supposed competitive multiplayer ladder games ( *cough* League of Legends/Starcraft *cough* ) boasting about how they work to make sure their games are balanced and fair and they're some of the most unbalanced ones out there, oh yes and point and click ganking is out of the question for this kind of thing too it would need to be properly interactive in some way.
Not putting you off, just giving you a fair warning, the only game I've seen that has come even close to being balanced for me was Counter Strike Source and even then that has it's problems with the AK-47 and the AWP as any gamer will tell you
if people find out that there's one weapon more powerful than all the others then they'll abuse the crap out of it to get Bitcoins, don't even get me started on games like EVE Online. If you're still a newbie to game development it maybe a good idea to create some kind of friendly sandbox multiplayer game where you do something creative for Bitcoin instead.